Forced induction on an SV motor?

I think the general consensus it the bottom end will be the limiting factor with standard internals. So defo upgrade the crank.etc

[yorkie_chris]

Have a look on TWF forum for arctic donkey and his engine.

Nitrous would be easier, there are some mods you could do for reliability. Commonly the crank snaps due to flywheel mass, so get rid of that for a start.


Why do this with 650? They're not the bike I'd want for 1/4 mile.

[SoulKiss]

Originally Posted by andrewsmith

the max you'd get without it going bang is around 90bhp N/A, but it'll cost around £6k to get that.

And for £6k you could buy a bike that does 100bhp+ brand new...

The engine isn't being fitted to a bike

[yorkie_chris]

I'd be seriously looking at the design choices you're making to need the SV engine.

For much much less money you could use a GSXR11 or something which with a turbo and a few hundred quid in mods can do 250bhp.


But for N/A tune on 650
http://www.twfracing.com/vbforums/sh...=5854#post5854

http://www.sv-portal.com/forums/show...=turbo+charged#

See here for a Turbo SV1000S

Thanks guys, I will check out that SV1000S-T build as well, due to the traction the wheels on the project I think around 90-100bhp is probably max before it becomes pointless as it can't get the power down. I was just seeing if running a low boost turbo/supercharger would be easier to get a tad more power without having to go for more expensive NA tuning.

Where is the best place to go for aftermarket parts like cranks?

The reason why I am going for an SV650 engine is the cost, parts are pretty cheap as its a fairly common V twin engine and makes pretty good power in a fairly compact unit with some easy performance increases such as changing out cams for the later model.

[embee]

A couple of topics here.

1 - you need to match the turbo more or less to the engine otherwise it simply won't work successfully. You can't just pick any old turbo.
There's loads of stuff on the web, but here seems quite a reasonable place at first sight.
Start with the compressor map and decide where your engine is going to run, pressure ratio and mass flow. If you run too small an engine on a big compressor the flow rate is too low and you'll be in surge (the compressor blades stall) and it'll be pants, so at the very least you need a compressor suited to around 100BHP, or something like 10 lbs/min airflow in those pesky old fashioned (and American) units, and aim to get the demand curve through the "eye" of the efficiency map, you can go past the optimum efficiency point to get max power but don't take it too far (turbo speed may limit it eventually).
You need to estimate the pressure ratio/mass flow curve your engine is going to run.
Be aware that diesel turbos won't tolerate the exhaust temps of gasoline engines (different turbine and housing materials used).
Decent matching of compressors and turbines needs a bit of understanding or advice.
Long headers from a V-twin aren't going to make life any easier to get decent response.
Typical compressor maps look like


2 - Superchargers are a lot easier to match air-wise, mechanical drive for them needs to transmit quite a lot of power so fairly decent belts required. There are superchargers around suited to that sort of airflow (Eaton items I've had some experience with, their M45 here is a smallish unit, the compressor map is in a link there). Again you don't want to run a too big unit, the efficiency drops off dramatically at the low mass airflow end (leakage round the rotors). You can easily play with drive ratios.

3 - Peak cylinder pressures aren't normally significantly higher than in N/A engines so mechanically the engine will probably be fine, peak pressures are usually closely tied to the knock limit for the chamber. If you run funny fuels (e.g. toluene mix) and run high CR plus high boost then peak pressures will get high and you're into bearing loads and gaskets and head bolting issues etc.

4 - Charge air cooling requirements are very similar for turbo and mechanical supercharging, typically try to keep induction air below 50C if at all possible for high power.

5 - Ultimately heat transfer from the heads is usually an issue, though if you're doing sprints you can get away with quite a lot which you wouldn't get away with for sustained periods. Excess fuelling is usually used to keep exhaust temps within sensible limits, for gasoline turbines around 900-950C is typical max. Fuel is an expensive coolant though. Expect to run maybe 10:1 AFR (lambda 0.7) or thereabouts if you're giving it real welly.

Sounds like it might be easier to run wet shot nitrous, I think I will do a bit of NA tuning first though, are there any big valves that you can fit?

[yorkie_chris]

Yes, not done too often and from what I hear not that reliable.

What is point of big valves and nitrous? Just add more gas, it is cheap, and much cheaper to replace when you get greedy and blow it up.

Nitrous system in entirety is less to put together than valves and machining would be.